Method and apparatus for electrodeposition



May?, 1929. 1 c. TuRNocK METHOD AND. APPARATUS FOR ELECTRODEPOSITIONFiled Dec. 17, 19,25

DWZ OFGOLD.

INVENTOR M C, w

Patented Nlay 7,- 1929.

UNITED STATES;

PATENT OFFICE;

LAWRENCE C. TURNOC'K, OF EDGEWQOD, PENNSYLVANI.

METHOD AND APPARATUS FOR ELECTODEPOSITION.

appncationm'ea December 17, 1925.V 'serial 1"N0.75,e57.

utility as applied'to the art'of electroplating comparatively largeobjects, such as band and orchestra instruments and the like, which haveAa relatively large surface area as compared with small articles ofjewelry and objects of similar nature. The word band 'j will hereinafterbe used generically as delimtive both of band and orchestra instruments,

the distinction between such instrumentsy quite frequently being in themanner of their Y ultimate use4 and not inI any features ofconstruction. y, i When plating articles such -as band instruments andthe like, and especially with' the metals goldand silver, the problem ofobtaining and linsuring. vaccuracy in the weight andthickness of thedeposit of metal is of extreme importance owing to the monef tary valuerepresented in v the deposited metals. Not only is it desirabletodeposit on such articles the minimum weight and thickness of metalcoating consistent with obtain.- ing a plated article that will be,guaranteed a serviceable life of reasonable length before the metalcoating becomes impaired, but it is likewise particularly desirableandim ortant. that there be uniformity in the Weig it and thickness ofmetal deposited per unit of exposed surfacearea on all such articlesir?- respective of their total surface area. v

Untilcomparatively recently, the only method of controllingorascertaining the amount of metal deposited in a plating bath has beento utilize an ammeter and estimate, the average current ilovvV during.the given period'of plating. The product of the estimated averagecurrent in amperes and the elapsed time in hours gives the approximatenumber of amperehours of electricity v passed, and enables the weight ofthe deposit of metal to be rough calculated. N

y prior United "51,527,13 5, granted February 17', 1925, there aredisclosed certain improvements in the art of electroplating and moreparticularlywith l respect to 'a method of obtaining great vac'- curacywith respect-to the coating on each individual article. The presentinvention is adapt-able invfaccordance with the disclosure tates PatentNo.-^

special problems have heretofore presented themselves due to the factthat the plating loperation has usually comprised, in` reality,

a ashing of the metal onto the articles. The currentflow as well as theduration of the plating period insuch cases are both so small thatdifficulty has been encountered in attempting to actually measure theequivalent quantity of electricity passed, from which the weight ofmetal 'deposited is in turn calculated. With some ofthesmallerarticles,such as jewelry and the like, it has heretofore beenproposed to utilize meters, but due to the diiiculty referred to, wheremeters have actu- Ially been used with gold plating, it has beencustomary to provide two meters connected 1n series for each bath. Oneof these meters has recorded both the auxiliary load and the quantity`of electricity passing to the plating bath, while the other hasrecorded'only the auxiliary load, The difference in reading between themeters has then been used 'to (letermine the amperehours of Pelectricitypassed, and from this value ythe amount of metal deposited. .Thisoperation, however, lis not entirely satisfactory as itV involves the-possibility of error both in meter readings and comparisons, as well asthe possibility of a difference in accuracy as between' the meters.

In vieri7 of these objections and difficulties I are necessarilycomparativelyl articles is necessarily expensive, and particuj larly sowhen plating with gold froma cy anide bath from which the rateof'deposit ofgold at the same current flow is substantially three tunesas rapid as when plated with gold from a gold chloride bath. In

order, however, to maintain and insure a given standard of excellence ofmetal coating, it is obvious that any error, where approximation is thebasis of operations, must be on the side of too heavy a deposit.

The present invention has for one of its objects to provide an improvedmethod of plating comparatively large articles, and particularly bandinstrnn'ients and the like, with gold or silver` Another object of theinvention is to `provide an .improved meter adapted for use with goldcyanide baths, and particularly such baths asaidapted for theapplication of protective or ornamental metal coatings to articles ofthecharacter referred to, or to other large articles of the general naturehereinafter referred to.

Still a'lnother object of the invention is to provide means of' keepingan exact record of all metal going onto the plated articles.I-Ieretofore, the manufacturers of band instruments for example, havebeen obliged to ascertainyihe amount of metah'and especially gold orsilver, plated on their product by noting the loss in weight of theiranodes from one day to the next. This method not only' involvesconsiderable error, but requires the removal of the anodes from thetanks, together with the loss of considerable time.

In the drawings, there are shown for purposes of illustration only,certain preferred embodiments of the present invention, it beingunderstood that the drawings do not deline the limits of my invention,Ias changes in the construction and operation disclosed therein maybemade without departing either from the Spirit of the invention or thescope of my "broader claims.

In the drawings:

Figure l is a diagrammatic view illustrating a plating bath and thecircuit connections therefor; i

Figure 2 isa front elevational view, largely-diagramrnatic,illustratinga meter constructed in accordanee with the present invention and havingits dial reading directly in units of gold deposited from a cyanidebath; and f Figure 3 is a view similar to Figure 2 illustrating ameterhaving its dial calibrated to read directly inunits of silver.

I have found thatwhen working with gold cyanide baths the theoreticalamount of gold deposited per aniperehonr outhc article being plated is4.7528 dwt. lurking on this basis I have had meters constructed in whichthe dials read directly in unit weights of metal deposited, the desiredreadings being obtained by construction, sub'dividing and lnarkmg thedials on the basis that each amperehour of electricity passing throughthe bath is equivalent to approximately 4.728 pennyweights of gold. Itwill be understood that the value or constant 4.728 is based on atheoretical plating etliciency of 100%, this constant varying as thepercentage of elliciency varies. It will be understood, however, thatthe present invention contemplates the use of this constant,-or certainmultiples` thereof on the basis of the etiiciency referred to, togetherwith any changes that m'ay be required by reason of this etliciency orcharacter of the bath.

In Figure 2 of the drawings` there is illustrated a meter M having adial 2 witli graduations 3 reading directly in pcnnyweights of gold inaccordance with the present invention. It will be obvious that onthebasis of the constant 4.728, other readings directly in grains orgrams may be readily calculated. Such a dial enables the meter to bereaddirectly in weights of gold and a predetermined weight having beencalculated for a given article or series of articles, a glance at thelneter will instantly show when the desired amount of metal has beendeposited. 'lhe use of such a meter makes it possible to obtain greataccuracy in the desired weights of deposited metal as well as greataccuracy inthe uniformity of plate on ditl'ercnt articles such as bandinstruments or thev like, thereby insuring the manufacturer against anygreat loss of metal by reason of deposits which are too heavy.Furthermore, the use of such a meter makes possible the adoption ofstandards of weight and thickness of gold or silver or other metal plateto differentsize instruments or similar articles, and likewise greatlyfacilitates the execution of such established standards. Heretoforesimilar articles have shown a lack of uniformity due to the absence ofan effective means of executing any given standards, accurate controlhaving been cxtremely difficult with respect to time and eurrent factorsin view of the personal equation and judgment of the operators.

wWhere silver is the metal being deposited, the constant is 2.588 dwt.of metal per amperehour, and the meters in such cases are similarlygraduated to read directly in unit weights of silver. Such a meter isindicated at M' in Figure 3 in which the dial 2 has graduations 3reading directly in penny- Weights ot silver, such meter being adaptedfor the silver plating of large objects of the character herein setforth.

The present invention also enables the weight and accordingly thethickness of the plating to be automatically controlled and the platingperiod definitely terminated wilhout the intervention of the operator.In Figure 1 ofthe d 'awings there is illustrated more or lessdiagrammatically one form of circuit involving the present invention. Inthis tigure there is indicated a source of direct current Gr having itspositive terminal connected to a line L. This'line may have any desirednumber of branches such as lindicated at 4.. and each of which may leadto one or more anodes A in a plating tank or tanks T. The cathode orcathodes C in each of these tanks are in turn connected to one side of ameter M of the character illustrated for example in Figure 2 of thedrawings. By' reason of the location of the meter on the cathode side ofthe circuit, they are only effective for measuring the actual How ofelectricity which has been effective on the cathodes. I have found sucha positioning of the meter to be highly desirable as compared with thepositioning on the anode side of the circuit, inasmuchl as the totalflow through the anodes may not be effective for plating purposes due toleakage or other losses. The opposite side of each of the meters isconnected to a common wire 6 leading to one terminal of a totalizingmeter TM, the connection of each meter to the comnion wire 6 preferablyincluding a circuit breaker 7 for the purposes hereinafter referred to.The opposite side` of the totalizing meter'is in turn connected to thenegative terminal of the source of current.

lEach of the meters may have a pointer 8 adapted to cooperate with thecalibrations 3 and a hand 9 adapted to be manually moved to any desiredposition. Having determined the desired amount of metal to he deposited,the hand 9 of each of the meters 3 will be set at the-desired point.Upon establishing a flowof electricity, the pointei 8 of eachof themeters will commence its travel in a clockwise direction in accordanceWith the actual* flow of electricity. .The hand 9 of each of the metersM has a connection 10 to one side of an auxiliary line fw, `while the`pointer 8 of each meter has a similar connection 11 to the opposite sideof an auxiliary line w', this last mentioned 'connection' including a'magnetic coil 12 cooperating with the circuit .breaker 7. By reason ofthis construction), when the pointer 8 coincides with the position'ofthe hand 9, the circuit will be closed through the` coil 12 therebyoperating the circuit breaker to open the circuit to the particular'bath controlled by that meter. It will thus be seen that the platingoperation can be automatically terminated atwill. 'y

|llhe totalizing meter TM may be of any desired construction adapted toread directly inA unit Weights of metal, whereby it is possible todetermine the actual amount of metal deposited by merely glancing at thetotalizing meter. This obviates the necessity of bodily removing theanodes from the bath and weighing the same as has heretofore beennecessary.

So far las I am aware, it has heretofore never been proposed to utilizea meter integratingt-he current and time factors on an electroplatingbath for comparatively large objects as herein. contemplated, and ithas,

-been proposed to utilize meters for use in plating large objects, it islikely that such practice would have followed the practice as applicableto smaller objects, and would have required the use of two meters foreach bath as herein set forth. By my invention the use 0f meters is notonly extended to a new field, but the manner of utilizing the same isradically changed so as to require only ay single meter in place of theplurality of meters heretofore required.

It will be apparent to those skilled in the art that the presentinvention is applicable to other large objects and-to the plating ofsuch objects with other metals. In this connection reference may be madetothe adaptability of the invention to use with automobile radiatorshells, bumpers, lamps and the like with protective or ornamentalcoatings of metals such as nickel, chromium, and cadmium, therebyaording the desired thickness of deposit per unit area of the platedarticle.

Certain advantages of the invention arise from the utilization of metersin the art as applicable to comparatively large objects, and moreparticularly to band instruments and the like, and especially metershavingv dials calibrated to read directly V,in unit weights of the metaldeposited.

Other advantages of the invention arise from the revision-of means in aplating operation o the character herein contemplated whereby the actualamount of gold or other.

metal utilized during any period, or over any time interval, may bequickly and accurately determined without the necessity of actuallyweighing the anodes.

Still other advantages of the invention arise from the provision of ameter for use with gold cyanide baths having its dial graduated to readdirectly in unit Weights of gold.

Still further advantages arise from the method of determining dialreadings for a meter as referred to by arranging the usual graduationsas used for amperehours on the basis of vone amperehour being equivalentto substantially 4.728 of ennyweights of gold with a 100% plating eciency.

I claim:

1. In an electro-plating system, the combination of an electro-platingbath, an anode and a cathode therein, a source of electromotive forceconnected to the anode, and a meter for indicating the amount of metaldeposited at the cathode in accordance with the current traversing thecathode, of electrically operated means for interrupting the electricalcircuit including the bath after a predetermined amount of metal hasbeen deposited, the circuit interrupting means being so connected totuating the interrupting means.

2. In an electro platlng system, a plurality of plating baths eachcontaining at least one comparatively large object to 'be plated andconstituting' a cathode, at least one anode in 'each bath, a.circuitincluding said anodes, means efl'ective while the anodes are inposition in their respective baths 'for indicating,r the amount of metaldeposited on the articles, and means controlled by the indicating meansfor separately interrupting the plating current ol" any bath when apredetermined amount ot' metal has been deposited therein.

3. In anelectro plating system, a plurality of plating baths eachcontaining an object to be plated and constituting a cathode, at leastone anode in each bath, a circuit includingr said anodes` meanseffective while the :modes are in position in their respective baths forindicatingr the amountI of metal deposited on said objects, andelectrically controlled means l'or separately interrupting the platingeurrent of any bath when a predetermined amount ot` metal has beendeposited'thereon.

In testimony whereof I have hereunto' set my hand.

LAWRENCE C. TURNOCK.

